the ultimate "do i need a 24pin PSU ?" thread

[RollWave]

i just want to say thanks do the guy who stepped up and created this thread! AWESOME JOB COVERING THE ISSUES!

 

[SirBrass]

Originally posted by: indianduddawg47
If you can switch to a 24 pin power supply with little to no cost, you might as well do it. It could potentionally save you problems, and it will futureproof your system.

I essentially can, since the 24 pin equivalent is available for less from newegg. Though I'm going to check out the local computer stores here in town as well. The graphics card comes monday, and I'd like the system to be completely ready before it gets here if I can.

 

[indianduddawg47]

well, why not? Compare the amps and everything just to make sure your not getting a crappier power supply.

 

[SirBrass]

I'm not, I checked. Amperage is reduced on the 12v rails (17A instead of 26A), but there are 2 17 volt rails, so that's cool, and one of which delivers 19 A (2nd one runs 17 A). Mwave sent the RMA # for the original pwr supply, and the appropriate pwr supply is coming from newegg.

 

[MJGunn]

Could use some advice.

Currently running a 2400+ Amd, A7N8x motherboard, 1 HD, 2 cd drives, and a X800 pro without a problem with my 350w antec power supply (20 pin).

Upgrading in about a month to a Asus A8N-E, A64 3200+, and a X800xl (other stuff will remain the same). What are the chances it'll run ok with my old power supply?

 

[SirBrass]

chances are slim, since the A8N-E will need 350 Watts MINIMUM under full load, and that 800xl is also going to want some power, and without those 4 pins, it's going to feel starved.

I'd recommend at least a 420 Watt supply with a 24 pin connector. I'd recommend this for you. It supplies plenty of amperage (17A) to the 12V rails (that's 17 amps per rail, not 17 amps split between the 2 rails), has 24 pins, and supplies a total of 430 Watts, and isn't too expensive either

 

[MJGunn]

Thanks for the help, I was actually looking at that one, and this one since its only $10 more for the extra 50w.

 

[SirBrass]

Yeah, that might be better, especially if you plan to add more power consuming devices (like an extra optical drive or two, or more hdd's), and for the cost it seems to be a better deal, IMO.

 

[element]

Originally posted by: flexy
(!) a single connector/wire on a PSU/connector is usually rated at a max. power draw of 6A. Wattage = VOLTS*A.
The maximum wattage for ONE 12V connector is therefore 72A

I'm sure you meant 72W and not amps OP. Might want to edit your first post. Just a minor typo which I'm sure everyone has figured out by now.

 

[Anubis169]

oki, soz if this has been answered before but i'm stumped.. i just boght a new OCZ 600w and it has a little slider that lets it be either 20-pin or 24-pin (see pictures)

this isn't the one used to provide juice to the CPU, but what should i do with it.. include it or detatch it and use the plug without it?

http://img.photobucket.com/albums/v497/Anubis169/Together.jpg

http://img.photobucket.com/albums/v497/Anubis169/Apart.jpg

 

[element]

Originally posted by: Anubis169
oki, soz if this has been answered before but i'm stumped.. i just boght a new OCZ 600w and it has a little slider that lets it be either 20-pin or 24-pin (see pictures)

this isn't the one used to provide juice to the CPU, but what should i do with it.. include it or detatch it and use the plug without it?

http://img.photobucket.com/albums/v497/Anubis169/Together.jpg

http://img.photobucket.com/albums/v497/Anubis169/Apart.jpg

if you have a 24 pin mobo attach it, if you have a 20 pin mobo then don't (can't anyway)

 

[Anubis169]

cheers v much, was worrying a bit there .. would i still need to have it in if i'm using a power cable to the GFX card instead of drawing power from the socket?

(mobo is the Asus A8N-E)

 

[SirBrass]

dunno. I think you should, just to be safe. The card will only draw the power it needs really.

 

[spazo]

Where are you guys getting these crazy power requirements from? A typical AMD Athlon n64 processor takes up about 70watts without any overclocking and when you divide 70/12 you get 5.8amps...Thats far from the 30+ amps you guys are recomending...

 

[bladephoenix]

It seems rather odd that my PSU unit has both a PCI-Express power connector AND a detachable 4 pin plug on the 24 pin mobo connector.

If the extra 4 pins on the 24 pin connector are solely for the purpose of a PCI-Express card, then it is rather redundant to include a "special" PCI-express power connector as well.

What is the point of that? It is just wasting wire!

anyways...OK...if I have this right, dual 12V rails are NOT actually seperate plugs. They are simply seperate rails. So 1 rail would send power to the CPU/Mobo and another rail would power any other device (Drives, etc)?

I am left to assume, then, the older ATX 1.3 PSUs powered the cpu and drives along the same 12V rail right? (Even though in ATX 1.3 there is a 12V plug specifically for the CPU) Is that why the Amps on my old PSU is 26a, while the new one is 2x18a? 18a is more than enough to handle most CPUs, so the remainer would be channeled into the other rail? I guess that would mean on ATX 1.3, the single 12V rail first powered the CPU and any power remaining would continue along the single 12V to power other devices?

I guess dual rails, in that case, provide a slight, however not really necessary, advantage by seperating the CPU and devices. I still don't think this is really that big of a deal though.

 

[ryansebiz]

will my Thermaltake 480 watt PSU provide enough power to my brand new computer? i bought a 20 pin - 24 pin cable - should i not use it? or should I upgrade to a dual 12V psu?

p.s. if i need to upgrade what do you think of this Thermaltake 460 watt dual 12v psu?

 

[Algere]

Originally posted by: spazo
Where are you guys getting these crazy power requirements from? A typical AMD Athlon n64 processor takes up about 70watts without any overclocking and when you divide 70/12 you get 5.8amps...Thats far from the 30+ amps you guys are recomending...

Well...

AMD's dual core has been said [by AMD] to consume up to a maximum of 9.1 amps & according to Tom's Hardware, they've stated that ASUS said 6800 Ultras in SLI can use around 14A. Already up to 23A combined, I suppose the remaining 7+ amps (30+ amp recommendation) could be left for drives, fans, etc.

 

[Algere]

Originally posted by: ryansebiz
will my Thermaltake 480 watt PSU provide enough power to my brand new computer?

I think so, assuming it can deliver stably what it's spec'd for. However I can't say what would happen if you installed a second 6600 GT.

Originally posted by: ryansebiz
i bought a 20 pin - 24 pin cable - should i not use it?

Based on what I've seen & read, I wouldn't use it. However that's up to you.

Originally posted by: ryansebiz
should I upgrade to a dual 12V psu?

If the Tt works why upgrade. If not, a dual 12V PSU (PSU trend these days) won't hurt.

Originally posted by: ryansebiz
p.s. if i need to upgrade what do you think of this Thermaltake 460 watt dual 12v psu?

At that price, I'd opt for a PSU brand with a better reputation of selling higher quality PSUs. Throughout this thread & forum + with the help of the forum's search function. You should be able to get an idea of what those brands are.

 

[Algere]

Assuming there isn't an extraordinary amount of drives & fans included, I don't see why not.

 

[JackMDS]

To be honest I am confused.

The issue should not be the Power supply, but rather the Motherboards.

If there is a component on the Motherboard that receive its Power from Pins 21-24 and you are using 20 pins Molex the motherboard should not work.

If the Motherboard works with 20 pins Molex it means that all components are receiving power.

I doubt that there is an arrangement for parallel power supplying the same components by pins 21-24. Parallel Power supplying is a source of noise, and might cerate a potential (voltage) differences problems.

Giving the current information I tend to think that the 4 additional pins are not really implemented as yet on the single CPU Entry Level Motherboards.

Currently EPS12V seems to be mainly implemented on High End Dual CPU Server Motherboards (and as you know these motherboards do not care too much about Graphics Cards).

I do not think that the answer lies with the Power Supply Brands, it is the Motherboard Brands that need to clarify it.

:sun:

 

[Homerboy]

Originally posted by: Arcanedeath
the extra 4 pins on the 24P PSU's are exclusively for powering PCI-E cards.... With a PCI-E card that doesn't have a 4 pin molex or 6 pin PCI-E connector (like most 6600GTs or X800XLs) you need a 24P PSU, it's that simple or you will have an unstable system under load.

I speak from experience on this one... and this guy is dead on correct.
6600GTs REQUIRE that extra 4pins (12V) to operate. No question

 

[JackMDS]

Originally posted by: Homerboy

Originally posted by: ArcanedeathI speak from experience on this one... and this guy is dead on correct.
6600GTs REQUIRE that extra 4pins (12V) to operate. No question

OK.

Assuming that you are correct then the tentative answer is: Check your Graphic Cards specs. To make sure that it does not need a 24pin Power Supply.

I have a DFI LAN, Party it works very well with 20pin 400W Power Supply and a PCI-E Asus 6200 using Windows XP x64.

:sun:

 

[Some1ne]

Originally posted by: flexy
Either consider a new PSU with dual rails with TWO 12V rails with *at least* 15A on EACH rail...or a STRONG 20pin PSU with plenty Amps on ONE rail...at least 25A or more !

Not here too...I see the common misconceptions about how big a PSU needs to be are just becoming more and more pervasive. Here are my current system specs:

MSI K8N Neo4 Platinum Mainboard
Athlon64 3000+ (Winchester) @ 2.46 GHz, vcore = 1.40V (+ 6.6% Over VID = 1.492V)
1 GB (2x 512) Corsair XMS PC4000 RAM @ CL2.5-3-4-6-1T, 2.85V, DCDDR528
Gigabyte geforce 6600GT video card w/ 128 MB RAM @ 540 MHz core, 1080 MHz RAM
2x 37 GB SATA 10K RPM WD Raptor HDD's in RAID-0
1x 160 GB WD 7200 RPM PATA HDD
1x 80 GB Maxtor 7200 RPM PATA HDD
NEC 4x DVD +/- R/RW drive
Benq 32X CD-R drive
Generic FDD
D-link DWL-520+ Wireless NIC
SoundBlaster Audigy MP3+
2x 120 mm case fans

...I am powering this on a single-rail Antec TruePower 380W PSU rated for 18A @ +12V, and the system has been rock solid and in near 24/7 operation for a very long time now. Attached to the wall outlet is a watt-meter that I got awhile back because I was tired of having people (not from here) continuously telling me (and other users) that running such a rig on an 18A @ +12V PSU was impossible due to power requirements. At idle, the meter reports a total power drain of only 160 Watts (it's actually slightly less than this, as the meter actually goes to my power strip, which powers some other devices, like my wireless router). During startup and under full load (prime95/gaming/3d benchmarks), the highest reading I've ever been able to obtain was about 230 watts. Note that this is the amount of power coming out of the wall, not how much power is actually being delivered to/demanded by the system. Let's be generous and say that my PSU is 80% efficient (it's actually a bit less than this, so actual system demand will be even less than computed here). This means that at full load, the system is only demanding about 184 watts of power, from *all* rails (3.3V, 5V, and 12V), not just the +12V rail, and clearly even if the demand were on the +12V rail exclusively, the PSU with its 18A @ +12V could still handle it.

Now I don't want to be misconstrued, and I'm certainly not saying that it's a good idea to go out and get some no-name $10 PSU that claims it can do 18A @ +12V or that doing so won't result in a fried MB, but at the same time any quality, name-brand (Antec makes some nice ones, as do OCZ and Enermax, although the latter two have long since jumped on the "let's put an insane amount of amps on the +12V rail because it's what people think they need and they'll pay a premium for it" bandwagon) PSU rated for 18A @ +12V should be adequate to power most systems. If you intend to run a dual-core chip, or 6800 class graphics cards in SLI, then there is justification for upping the recommendation to 24A @ +12V (or dual-rails) or more, but for most systems, 18A is plenty for the time being.

 

[SirBrass]

from what I can tell, antec hasn't jumped on that bandwagon. my antec 450Watt psu has 17A and 19A on the dual 12v rails.

 

[kingrygar]

Hey guys!

I have just built a new computer using:

Foxxcon Winfast nForce4 (24pin ps input)
Ati 800XL
AMD 3500+
1 GB Ram

Anyways I get all this stuff together, and now I find out my Antec TruePower430 has a 20 pin plug! In my motherboard manual, it says "we STRONGLY recommend using a 24pin power supply, but if you must use a 20pin, insert it as shown.

Well, I gently put the computer together, hook everything up, but nothing happens at all when I push the power button! I unplugged the PS and did the "short" trick, and the power supply runs fine and all the fans spin. But while connected to the motherboard, nothing happens. I have tried everything I know and still nothing.

Do you think the problem is my lack of 24pins? It seems pretty impotant judging by the motherboard manual.

I have already ordered this power supply:
http://www.newegg.com/Product/Product.asp?Item=N82E16817103928

I am just hoping this will work! Does anyone have any ideas?

Thanks for your time!